Goals from Bafétimbi Gomis, Loïc Perrin and Dimitri Payet saw ten-time French champions AS Saint-Etienne prevail after a frantic start to the match at FC København.
Morten Nordstrand missed a penalty for the home side just three minutes after French international Gomis had headed St-Etienne into a second-minute lead. Cesar Santin converted from the spot for København after Perrin had doubled the visitors' advantage, but Payet struck with 25 minutes to go to give the beaten 1975/76 European Champion Clubs' Cup finalists a winning start in Group G.
Gomis spearheaded a three-man St-Etienne attack and made an almost immediate impact as Payet found space on the left before crossing for his team-mate to head into the top-left corner. Sylvain Monsoreau's foul on Santin in the box soon after handed København a chance to level, but goalkeeper Jody Viviani pushed Nordstrand's effort wide.
The hosts promptly took control as the pace slowed, but Viviani proved equal to their threats, saving from an Ulrik Laursen header before Perrin finished from 10 metres following a ball from Gomis eight minutes before the break. Paulo Machado's long-range effort then required confident handling from København keeper Jesper Christiansen.
The Danish side made a double substitution in the 57th minute with Ailton Almeida and William Kvist replacing Nordstrand and Hjalte Nørregaard and a couple of minutes later were back in the game. Efstathios Tavlaridis was penalised for another foul on Santin in the box and the Brazilian stepped up to convert the penalty. However, Payet restored the two-goal cushion from six metres out after 65 minutes and though Santin forced another save from Viviani, the visitors held on to take the points.